electronic communication system unit one

communication system

1. UNIT 1
ELC 222

2. Elements of an Electronic Communication
System
An electronic communication system is a set of electronic devices that work together to
send information from one place to another.

3. Information Source 1.
The information source in a communication system is where the
message or data originates. It can be a person speaking, a
computer sending files, a camera capturing images, or any device
or medium that generates the content to be communicated.
2. Transducer
The transducer is a device that converts one form of energy into
another. In communication systems, it converts physical signals
(like sound or images) into electrical signals for transmission. For
example, a microphone (transducer) converts your voice (sound
waves) into an electrical signal.

4. 3. Transmitter
It converts the electrical message signal into a form suitable for
transmission on the physical medium or channel. It might amplify
the signal, modulate it onto a carrier wave (for wireless
communication), or otherwise process it to make it suitable for
sending over the channel.
4. Channel and Noise
The channel is the physical medium through which the message
travels from the sender to the receiver. It could be a physical wire
(like a coaxial cable), fiber optics, or wireless (like radio waves
through the air).
Noise is any unwanted random signal that interferes with the
transmission and reception of the message signal.

5. 5. Receiver
It reproduces the message in electrical form from the distorted
received signal.
4. Output transducer
It converts the received electrical message signal back to its
original form. For example, a speaker (output transducer) converts
the electrical signals back into sound waves that you can hear.

6. Sources of Information

7. Channel

8. Classification of Channels/ Transmission Medium

9. Guided Medium: Guided media involves a physical path that guides
the signal between the transmitter and receiver. The signal is
confined within cables or wires.
Unguided Medium: Unguided media, also known as wireless media,
does not use a physical conductor. Instead, they transmit signals
through the air or vacuum, using electromagnetic waves.

10. Types of Guided Media / Cable

11. Twisted Pair cable
Consists of two insulated
conductors twisted together to
form a spiral.
The twisted reduces crosstalk.
It can be shielded (STP) or
unshielded (UTP).
Commonly used in telephone
lines and ethernet cables.

13. Co-axial cable
Consists of the inner conductor and the outer conductor separated
by insulating material.
The inner conductor is used to transmit the signal while the outer
conductor acts as ground and also as a shield against noise.
Compared to the twisted pair cable, it offers better noise immunity
and better data rates.
Costlier than twisted pair but cheaper than optic fibres.

15. Optical Fibre cable
It consists of an inner glass core surrounded by a glass cladding which
has a lower refractive index.

17. messages are sent as light signals.
Light is shown in at one end of the fiber via a laser or LED.
Light hits the boundary between the fiber and the cladding at an
angle greater than the critical angle.
This ensures that light travels down the cable via total internal
reflection.

20. Unguided Media

23. Classification of Electronic Communication
Systems
Also called
broadband
transmission

27. Modulation and Demodulation
Modulation is the process whereby the transmitter modifies the
characteristic of the carrier signal in accordance of the message
signal.
In the modulation process there are two signals used: the modulating
signal or the message signal and the carrier signal
Some parameter (amplitude, frequency of phase) of the carrier is
modulated in accordance to the modulating / baseband signal.
The modulated signal is then transmitted over the medium.
The receiver demodulates the original message from the degraded
received signal.

28. Modulation and Demodulation
Modulation is the process whereby the transmitter
modifies or changes some characteristic of the
carrier signal in accordance with the message signal.
The source information is impressed upon a carrier-
wave by changing or modifying some characteristic
of the carrier wave.
.

29. Modulation and Demodulation
The message signal is called baseband signal and the modulated
signal is called the bandpass signal.
The modulated signal (bandpass signal) is then transmitted over the
medium.
The receiver demodulates the original message from the degraded
received signal.

30. Modulation and Demodulation

31. The Need For Modulation

37. Analog Modulation Digital Modulation

41. Phase Modulation

42. Analog Pulse Modulation

45. Multiplexing
Multiplexing is the name given to techniques, which
allow more than one message signal to be transferred
via the same communication channel at the same
time (simultaneously).
A channel will offer a specified bandwidth, which is
available for a time t. Thus, with reference to the
channel there are 2 ‘degrees of freedom’, i.e.
bandwidth or frequency and time.
.

46. A device called a multiplexer (often shortened to "mux") combines
the input signals into one signal. When the multiplexed signal needs
to be separated into its component signals, a device called a
demultiplexer (or "demux") is used.

52. Limitations of a Communication System